{"id":36312,"date":"2024-06-14T18:56:05","date_gmt":"2024-06-14T16:56:05","guid":{"rendered":"https:\/\/karmaka.de\/?p=36312"},"modified":"2024-06-14T18:56:06","modified_gmt":"2024-06-14T16:56:06","slug":"identification-of-a-primordial-high-d-h-component-in-the-matrix-of-unequilibrated-ordinary-chondrites","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=36312","title":{"rendered":"Identification of a primordial high D\/H component in the matrix of unequilibrated ordinary chondrites<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Helen Grant, Romain Tart\u00e8se, Rhian Jones, Laurette Piani, Yves Marrocchi<\/p>\n\n\n\n<p>Geochimica et Cosmochimica Acta<br>In Press, Journal Pre-proof, Available online 14 June 2024<\/p>\n\n\n\n<p><a href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0016703724002898\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;Deuterium to hydrogen isotope ratios in unequilibrated ordinary chondrites (UOCs) which have undergone little-to-no thermal metamorphism pose an interesting problem when looking at water in the early Solar System. Bulk chondrite studies have shown that UOCs of the lowest subtypes have D\/H ratios as high as comets from the outer Solar System, which, along with bulk UOC water abundances, decrease with thermal metamorphism. Since bulk UOC analyses represent a complex mixture of organic and hydrated phases, it is not clear what phase(s) is responsible for the high bulk D\/H values. In this study, we report in situ secondary ion mass spectrometry (SIMS) measurements of the H isotope composition of the fine-grained matrix of UOCs with petrological subtypes ranging from 3.00 to 3.9. We find that for matrix areas in UOCs of petrologic subtype \u22653.2, correlations between D-rich organic material and D-poor phyllosilicates give relatively D-poor intrinsic water isotopic compositions, with \u03b4D values between \u2212320\u202f\u00b1\u202f91\u202f\u2030 and \u221271\u202f\u00b1\u202f71\u202f\u2030, which are inherited from parent body accretion. Therefore, we conclude that OC parent bodies accreted D-poor water ice that had an H isotopic composition similar to that of CM and CV chondrite parent bodies. We find that matrix in UOCs of the lowest subtypes (Semarkona, Bishunpur, and Ngawi) show similar water and organic H isotope compositions to higher type UOCs. Our in situ analyses also show that matrix areas in these pristine UOCs contain a third, thus far unidentified, component that carries the high D\/H signature, with \u03b4D values up to \u223c6000\u202f\u2030. We propose that this component is pristine amorphous silicates preserved from the molecular cloud or early protoplanetary disc that is extremely sensitive to thermal and aqueous alteration on asteroidal parent bodies.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Helen Grant, Romain Tart\u00e8se, Rhian Jones, Laurette Piani, Yves Marrocchi Geochimica et Cosmochimica ActaIn Press, Journal Pre-proof, Available online 14 June 2024 LINK (OPEN ACCESS) &#8220;Deuterium to hydrogen isotope ratios in unequilibrated ordinary chondrites (UOCs)&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61,58,7,62,2961],"tags":[1216,1842,493,2932,428,1840,6129,1807,158,4693,2634],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36312"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=36312"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36312\/revisions"}],"predecessor-version":[{"id":36313,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/36312\/revisions\/36313"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=36312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=36312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=36312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}